Warkentin began his career in technical illustrating, advertising, album cover design and magazine illustration. Following his stint on Star Trek he wrote the "Flash Gordon" strip for several years in the early 1990s. He worked for Filmation in 1985 on the TV animated series He-Man and the Masters of the Universe and She-Ra, Princess of Power. Later, working for both Disney and Warner Bros., Warkentin won an Emmy for his work on Animaniacs.